function Stack(){
    this.arr=[];
}

Stack.prototype.push=function(item){
    this.arr.push(item);
}

Stack.prototype.pop=function(){
    if(this.arr.length>0){
        return this.arr.splice(this.arr.length-1,1)[0];
    }
    
    return null;
}

Stack.prototype.isEmpty=function(){
    return this.arr.length===0;
}
export default Stack